Many vehicles, such as aircraft, include display systems to convey flight path and/or flight management information. One type of display system is an enhanced vision (EV) system. An EV system uses an infrared (IR) and/or millimeter wave (MMW) video camera to sense thermal signatures of objects and to render images based on the sensed thermal signatures on a display. Although the EV system, with the ability to see in reduced visibility conditions, displays particular features/objects which may be overwhelmed by surrounding or adjacent image areas having similar thermal signatures. FIG. 1 is an EV image 100 showing a runway 102, a taxiway 104, and various other objects around the airport, such as buildings 106 and roads 108. FIG. 1 also includes dark areas, providing little thermal output, such as the sky 110 and terrain 112. Although image processing can improve image quality, the images presented to the vehicle operator still may be insufficient.
Another type of display system is a synthetic vision (SV) system. An SV system operates by rendering an image based on pre-stored database information. For example, referring to FIG. 2, an image 200 created from the pre-stored database information may include flight management data 202, e.g., heading, altitude, and speed, superimposed on a synthetic rendering of terrain 204 and objects such as a runway 206 and a taxiway 208, some of which may be of a range for detection by an EV system or not clearly shown in an EV images. Thus, SV images can provide the vehicle operator with an effective interface for vehicle control. SV image integrity, however, is limited by the integrity of the information pre-stored in the database. Accordingly, incomplete and/or outdated database information can result in SV images of limited value.
Some display systems display both an SV image and an EV image display. For example, as a fused (merged) image (such as overlaying an EV image onto an SV image) or as a side-by-side display. The images may be indexed at the time of camera installation, e.g., by aligning an EV image sensor to ensure that the sensor and the SV view are indexed. Such a process may be periodically repeated during normal course of maintenance to assure proper alignment. Although such an overlaid “enhanced synthetic vision system” display may be useful, the display can be confusing, noisy, and difficult to interpret. For example, pixel averaging or alpha blending between SV and EV images can result with views being obscured with noisy or non-useful information, making it difficult for the pilot to interpret the information encoded on the display.
Referring to FIG. 3, the EV image 100 and the SV image 200 are merged into one image 300. However, the merged image 300 is difficult to interpret. The merged image 300 includes portions that are dark, for example, the black area 302, making it difficult to discern what portions of the merged image are provided by the EV image 100 and the SV image 200. Furthermore, the dark portion 302 may prevent the viewing of a portion of the SV image 200.
Accordingly, it is desirable to provide an apparatus and method for displaying SV and EV images that are relatively easy to interpret and that differentiates between the SV image and the EV image. Furthermore, other desirable features and characteristics of exemplary embodiments will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.